JP2022098063A - Manufacturing method of printed wiring board - Google Patents

Abstract

To form a plating uniformly even if there is eccentricity in through hole arrangement density.SOLUTION: A plurality of first penetration holes 4-1 are formed at a first pitch on a double-sided copper clad laminated board 3. A first plating film is formed on a first copper foil; a second plating film is formed on a second copper foil; and a first through hole conductor 5-3 is formed within the plurality of first penetration holes 4-1. A surface of the first copper foil and the second copper foil is made flush with a surface of the first through hole conductor 5-3 by polishing or etching, and a plurality of second penetration holes 4-2 are formed at a second pitch with respect to the adjacent first penetration holes. A third plating film and a fourth plating film are formed on the flush surfaces of the copper foils and the first through hole conductor 5-3, and a second through hole conductor 5-6 is formed within the plurality of second penetration holes 4-2. The surface of the copper foils is made flush with a surface of the first through hole conductor 5-3 and the second through hole conductor 5-6 by polishing or etching and thereafter, a first conductor circuit 8-1 and a second conductor circuit 8-2 are formed from a fifth plating film and a sixth plating film which are formed on both the surfaces.SELECTED DRAWING: Figure 1F

Description

The present invention relates to a method for manufacturing a printed wiring board having a perforated through hole.

Conventionally, in a printed wiring board having a perforated through hole, it has been required to increase the density of the through hole arrangement (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-72454

4 (a) to 4 (d) are diagrams showing a method of manufacturing a conventional printed wiring board having a perforated through hole, respectively. First, a through hole 54 is formed by a drill in a double-sided copper-plated laminated plate 53 composed of an insulating substrate 51 and copper foils 52 formed on both surfaces thereof, and a tubular through-hole conductor 55 is formed on the exposed insulating substrate 51. , A plating film 59 is formed on the copper foil 52 (FIG. 4A). Next, the through-hole conductor 55 is filled with the filling resin 56, and the filling resin 56 is polished so as to be flush with the through-hole conductor 55 and the plating film 59 (FIG. 4B). Next, the plating film 57 is formed on both surfaces where the filling resin 56, the through-hole conductor 55, and the plating film 59 are flush with each other (FIG. 4 (c)). Further, for example, a subtractive method is applied to the plating film 57 to form a conductor circuit 58 (FIG. 4 (d)).

In the printed wiring board manufactured by the above-mentioned manufacturing method, if the through-hole arrangement density is uneven, the plating thickness of the through-hole conductor 55 and the plating film 59 decreases in the place where the through-hole density is high, and the through-hole density is low. At the location, the plating thickness of the through-hole conductor 55 and the plating film 59 becomes thicker. Therefore, there is a problem that the plating thickness of the through-hole conductor 55 on the inner wall of the through hole 54 and the plating film 59 on the surface of the insulating substrate 51 varies. In that case, the variation in the plating thickness reduces the process capability of wiring formation by the subtractive method, or becomes a barrier to the wiring formation itself.

In the method for manufacturing a printed wiring board of the present invention, an insulating substrate having a first surface, a second surface opposite to the first surface, and a first copper laminated on the first surface of the insulating substrate. A double-sided copper-clad laminate formed of a foil and a second copper foil laminated on the second surface is prepared, and a plurality of first penetrations are made in the double-sided copper-clad laminate at a first pitch. Forming a hole, forming a first through-hole conductor inside the plurality of first through holes, forming a first plating film on the first copper foil, and forming the second copper foil. By forming the second plating film on the first surface and removing a part of the first plating film and the first through-hole conductor exposed from the first surface, the first copper is on the first surface side. By forming a first plane formed by the foil and the first through-hole conductor, and removing a part of the second plating film and the first through-hole conductor exposed from the second surface, the said A place where a second plane formed by the second copper foil and the first through-hole conductor is formed on the second surface side and the plurality of first through holes of the double-sided copper-clad laminate are not formed. In addition, a plurality of second through holes are formed at a second pitch with respect to the adjacent first through holes, and a second through hole conductor is formed inside the plurality of second through holes. A third plating film is formed on the first copper foil exposed from the first plane and on the first through-hole conductor, and on the second copper foil exposed from the second plane and the first. By forming the fourth plating film on the through-hole conductor and removing a part of the third plating film and the second through-hole conductor, the first copper foil and the first copper foil are on the first surface side. By forming a third plane formed by the 1 through-hole conductor and the 2nd through-hole conductor, and by removing a part of the 4th plating film and the 2nd through-hole conductor, the 2nd surface side To form a fourth plane formed by the second copper foil, the first through-hole conductor, and the second through-hole conductor, and on the first copper foil exposed from the third plane and the first. Forming a fifth plating film on the through-hole conductor and on the second through-hole conductor, and on the second copper foil exposed from the fourth plane, on the first through-hole conductor, and on the second through-hole conductor. At least including forming a sixth plating film on a conductor, forming a first conductor circuit from the fifth plating film, and forming a second conductor circuit from the sixth plating film.

It is a figure for demonstrating one step in one Embodiment of the manufacturing method of the printed wiring board of this invention. It is a figure for demonstrating one step in one Embodiment of the manufacturing method of the printed wiring board of this invention. It is a figure for demonstrating one step in one Embodiment of the manufacturing method of the printed wiring board of this invention. It is a figure for demonstrating one step in one Embodiment of the manufacturing method of the printed wiring board of this invention. It is a figure for demonstrating one step in one Embodiment of the manufacturing method of the printed wiring board of this invention. It is a figure for demonstrating one step in one Embodiment of the manufacturing method of the printed wiring board of this invention. (A) to (d) are diagrams for explaining a subtractive construction method for forming a first conductor circuit and a second conductor circuit from a fifth plating film and a sixth plating film, respectively. (A) to (d) are diagrams for explaining a semi-additive method for forming a first conductor circuit and a second conductor circuit from a fifth plating film and a sixth plating film, respectively. (A) to (d) are diagrams for explaining each step in one embodiment of the conventional method for manufacturing a printed wiring board, respectively.

1A to 1F are diagrams for explaining each step in one embodiment of the method for manufacturing a printed wiring board of the present invention, respectively. In the examples shown in FIGS. 1A to 1F, the dimensions of each member are described with dimensions different from the actual dimensions so that the features of the present invention can be better understood. Hereinafter, an embodiment of the method for manufacturing a printed wiring board of the present invention will be described with reference to FIGS. 1A to 1F.

First, as shown in FIG. 1A, an insulating substrate 1 having a first surface 1-1, a second surface 1-2 on the opposite side of the first surface 1-1, and a first surface 1-1 of the insulating substrate 1 A double-sided copper-clad laminate 3 formed of the first copper foil 2-1 laminated on the top and the second copper foil 2-2 laminated on the second surface 1-2 is prepared, and both sides are prepared. A plurality of first through holes 4-1 are formed in the copper-clad laminate 3 at the first pitch. After that, it is exposed from the first plating film 5-1 on the first copper foil 2-1 and the second plating film 5-2 on the second copper foil 2-2, and from a plurality of first through holes 4-1. A tubular first through-hole conductor 5-3 is formed on the insulating substrate 1. The first pitch P1 of the first through hole 4-1 may be a pitch having the same distance or a pitch having a different distance for each pitch, as long as it is preferably 600 μm or more. In the example shown in FIG. 1A, in the three first through holes 4-1 shown, the first pitch P1 of the two first through holes 4-1 on the left side and the first through holes 4-1 on the right side The distance is different from that of the first pitch P1.

Here, as the double-sided copper-clad laminate 3, a commercially available double-sided copper-clad laminate (CCL) can be used. The first through hole 4-1 is formed by subjecting the double-sided copper-clad laminate 3 to a conventionally known method, for example, drilling or laser (CO ₂ , UV-YAG, excimer, etc.) processing. be able to. Further, after the formation of the first through hole 4-1 and before the formation of the first through hole conductor 5-3, the surfaces of the first copper foil 2-1 and the second copper foil 2-2 and the first penetration of the insulating substrate 1 are formed. It is preferable to remove the residue generated by the formation of through holes in the inner wall of the hole 4 by, for example, a desmear treatment using permanganate + sodium hydroxide or a desmear treatment using plasma using CF ₄ . Further, the first plating film 5-1 and the second plating film 5-2 and the first through-hole conductor 5-3 are formed by electroless copper plating and subsequent electrolytic copper plating.

Next, as shown in FIG. 1B, the first plating film 5-1 exposed from the first surface 1-1 and a part of the first through-hole conductor 5-3 are removed by polishing or etching. A first plane 10-1 formed by the first copper foil 2-1 and the first through-hole conductor 5-3 is formed on the one-side 1-1 side. Similarly, by polishing or etching, a part of the second plating film 5-2 and the first through-hole conductor 5-3 exposed from the second surface 1-2 is removed to the second surface 1-2 side. A second plane 10-2 formed by the second copper foil 2-2 and the first through-hole conductor 5-3 is formed. Here, as a method for polishing both surfaces of the double-sided copper-clad laminate 3, as conventionally known methods, methods such as buffing, belt polishing, and surface polishing can be used, and the polishing method depends on the product specifications. Use properly. Further, as a method for etching both surfaces of the double-sided copper-clad laminate 3, a method of etching both surfaces of the double-sided copper-clad laminate 3 with an etching solution can be used, as is conventionally known.

Next, as shown in FIG. 1C, the double-sided copper-clad laminate 3 is adjacent to a portion where a plurality of first through holes 4-1 are not formed (in this example, between adjacent first through holes 4-1). A plurality of second through holes 4-2 are formed at a second pitch with respect to the first through holes 4-1 to be formed (in this example, one place is formed between the adjacent first through holes 4-1). There). After that, the third plating film 5-4 is on the first copper foil 2-1 exposed on the first flat surface 10-1 and the first through-hole conductor 5-3, and the second surface is exposed on the second flat surface 10-2. A fourth plating film 5-5 is formed on the copper foil 2-2 and the first through-hole conductor 5-3, and a second through-hole conductor 5-6 is formed inside the plurality of second through holes 4-2. .. The second pitch of the second through hole 4-2 may be a pitch of the same distance or a pitch of a different distance for each pitch as long as it is preferably 300 μm or more. In the example shown in FIG. 1C, in the two second through holes 4-2 shown, the second pitch P2 with respect to the first through hole 4-1 on the left side of the second through hole 4-2 on the left side and the right side. The distance is different from the second pitch P2 with respect to the first through hole 4-1 to the left of the second through hole 4-2. The formation of the second through hole 4-2 and the formation of the third plating film 5-4, the fourth plating film 5-5, and the second through hole conductor 5-6 are the first through hole 4-1 and the first. This is the same as the formation of the plating film 5-1 and the second plating film 5-2 and the first through-hole conductor 5-3.

Next, as shown in FIG. 1D, by removing a part of the third plating film 5-4 and the second through-hole conductor 5-6 by polishing or etching, the first surface 1-1 side is first. A third plane 10-3 formed by the copper foil 2-1 and the first through-hole conductor 5-3 and the second through-hole conductor 5-6 is formed. Similarly, by removing a part of the 4th plating film 5-5 and the 2nd through-hole conductor 5-6 by polishing or etching, the 2nd copper foil 2-2 and the 2nd copper foil 2-2 are on the 2nd surface 1-2 side. A fourth plane 10-4 formed by the first through-hole conductor 5-3 and the second through-hole conductor 5-6 is formed. The polishing method and the etching method are the same as those in the above-mentioned example.

Next, as shown in FIG. 1E, a fifth on the first copper foil 2-1 exposed on the third plane 10-3, on the first through-hole conductor 5-3, and on the second through-hole conductor 5-6. The sixth plating film 7 on the plating film 7-1, the second copper foil 2-2 exposed on the fourth flat surface 10-4, the first through-hole conductor 5-3, and the second through-hole conductor 5-6. -Forms with -2. The fifth plating film 7-1 and the sixth plating film 7-2 form the first plating film 5-1 and the second plating film 5-2, the third plating film 5-4, and the fourth plating film 5-5. Similarly, it can be formed by electrolytic copper plating followed by electrolytic copper plating.

Finally, as shown in FIG. 1F, the fifth plating film 7-1 is processed to form the first conductor circuit 8-1 on the first surface 1-1 of the double-sided copper-clad laminate 3. Similarly, the sixth plating film 7-2 is processed to form the second conductor circuit 8-2 on the second surface 1-2 of the double-sided copper-clad laminate 3. In order to form the first conductor circuit 8-1 and the second conductor circuit 8-2 from the fifth plating film 7-1 and the sixth plating film 7-2, a conventionally known subtractive method or semi-additive method is used. Can be used. After that, an interlayer insulating layer is formed on the first conductor circuit 8-1 and the second conductor circuit 8-2 which are patterned on both the front and back surfaces, and a predetermined number of conductor layers and interlayer insulating layers are formed on the interlayer insulating layer. By doing so, the build-up structure can be formed only in a predetermined layer.

Hereinafter, as a processing method used when forming the first conductor circuit 8-1 and the second conductor circuit 8-2 from the fifth plating film 7-1 and the sixth plating film 7-2, a subtractive method and a semi-additive method are used. Will be described with reference to FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (d), respectively. In the examples shown in FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (d), the same members as those shown in FIGS. 1A to 1F are designated by the same reference numerals, and the description thereof will be omitted. do.

2 (a) to 2 (d) are diagrams showing the steps of one embodiment for forming the first conductor circuit 8-1 and the second conductor circuit 8-2 according to the subtractive method, respectively. First, with respect to the double-sided copper-clad laminate 3 (corresponding to FIG. 1E) in which the fifth plating film 7-1 and the sixth plating film 7-2 shown in FIG. 2 (a) are formed, FIG. 2 (b) shows. As shown, the resist 9 is formed at a position where the first conductor circuit 8-1 and the second conductor circuit 8-2 should be formed. After that, etching was performed on the double-sided copper-clad laminate 3 on which the resist 9 was formed, and as shown in FIG. 2C, the fifth plating film 7-1 and the sixth plating film 7-2 of the portions other than the resist 9 were etched. And the first copper foil 2-1 and the second copper foil 2-2 are removed to expose the insulating substrate 1. Finally, the resist 9 is removed to form the first conductor circuit 8-1 and the second conductor circuit 8-2 as shown in FIG. 2D. A known method can be used for forming the resist 9, etching, and removing the resist 9.

3 (a) to 3 (d) are diagrams showing the steps of one embodiment for forming the first conductor circuit 8-1 and the second conductor circuit 8-2 according to the semi-additive method, respectively. First, as shown in FIG. 3A, a resist is formed on the surface of the double-sided copper-clad laminate 3 in the state shown in FIG. 1D at a position where the first conductor circuit 8-1 and the second conductor circuit 8-2 are not formed. 9 is formed. Next, as shown in FIG. 3 (b), the surfaces of the first copper foil 2-1 and the second copper foil 2-2 and the through-hole conductor 5-3 (5) of the double-sided copper-plated laminated plate 3 in which the resist 9 does not exist. A fifth plating film 7-1 and a sixth plating film 7-2 are formed on the surface of -6). Next, as shown in FIG. 3C, the resist 9 is removed to form the first conductor circuit 8-1 and the second conductor circuit 8-2. Finally, as shown in FIG. 3D, the surface is etched to form a first copper foil 2-1 and a second copper foil other than the portions of the first conductor circuit 8-1 and the second conductor circuit 8-2. 2-2 is removed to expose the insulating substrate 1 to form the final first conductor circuit 8-1 and second conductor circuit 8-2. Also in this example, known methods can be used for forming the resist 9, etching, and removing the resist 9. The semi-additive method is more suitable for forming a narrow-pitch conductor pattern than the subtractive method.

In the method for manufacturing a printed wiring board of the present invention described above, the first pitch of the first through hole 4-1 is 600 μm or more, and the second through hole 4-2 with respect to the adjacent first through hole 4-1 is the first. The pitch of 2 is preferably 300 μm or more. The through-hole densities formed at each stage are dispersed, and the plating thickness of the first and second core through-hole conductors can be made uniform. Further, it is preferable that the hole diameters of the plurality of first through holes 4-1 are 150 μm or more and 300 μm or less, and the hole diameters of the plurality of second through holes 4-2 are 100 μm or more and 200 μm or less. Since the plurality of first through holes can have a larger hole diameter than the plurality of second through holes, they can be used as power conductors. Since the plurality of second through holes have a smaller hole diameter than the plurality of first through holes, they can be used as signal conductors.

In the present invention, the order of forming the first through-hole conductor 5-3, the first plating film 5-1 and the second plating film 5-2 is not particularly limited, but the first through-hole conductor 5-3 is formed. It is preferable that the formation of the first plating film 5-1 and the formation of the second plating film 5-2 are performed at the same time. Similarly, the order of forming the second through-hole conductor 5-6, the third plating film 5-4, and the fourth plating film 5-5 is not particularly limited, but the formation of the second through-hole conductor 5-6 and the first It is preferable that the formation of the 3 plating film 5-4 and the formation of the 4th plating film 5-5 are performed at the same time. Similarly, the formation order of the 5th plating film 7-1 and the 6th plating film 7-2 is not particularly limited, but the formation of the 5th plating film 7-1 and the formation of the 6th plating film 7-2. Is preferably performed at the same time.

According to the printed wiring board of the present invention described above, by forming the through-holes in two stages, it is possible to uniformly form the plating even if the through-hole arrangement density is uneven. In addition, the hole diameter and conductor thickness can be changed for through-holes in the same layer, increasing the degree of freedom in through-hole design.

In the method for manufacturing a printed wiring board of the present invention, the through-hole formation is divided into two stages, but even when the through-holes are formed in two or more stages, the same effect as that of the present invention can be obtained. Needless to say, you can do it.

1 Insulated Substrate 1-1 1st Surface 1-2 2nd Surface 2-1 1st Copper Foil 2-2 2nd Copper Foil 3 Double-sided Copper Plated Laminated Plate 4-1 1st Through Hole 4-2 2nd Through Hole 5 -1 1st plating film 5-2 2nd plating film 5-3 1st through-hole conductor 5-4 3rd plating film 5-5 4th plating film 5-6 2nd through-hole conductor 7-1 5th plating film 7-2 6th plating film 8-1 1st conductor circuit 8-2 2nd conductor circuit 9 Resist 10-1 1st plane 10-2 2nd plane 10-3 3rd plane 10-4 4th plane

Claims (6)

An insulating substrate having a first surface, a second surface opposite to the first surface, a first copper foil laminated on the first surface of the insulating substrate, and laminated on the second surface. To prepare a double-sided copper-clad laminate made of the second copper foil,
Forming a plurality of first through holes at the first pitch in the double-sided copper-clad laminate,
Forming a first through-hole conductor inside the plurality of first through holes, and
Forming the first plating film on the first copper foil and
Forming a second plating film on the second copper foil and
By removing a part of the first plating film and the first through-hole conductor exposed from the first surface, the first copper foil and the first through-hole conductor are formed on the first surface side. Forming the first plane and
By removing a part of the second plating film and the first through-hole conductor exposed from the second surface, the second copper foil and the first through-hole conductor are formed on the second surface side. Forming the second plane and
A plurality of second through holes are formed at a second pitch with respect to the adjacent first through holes at a portion of the double-sided copper laminated plate where the plurality of first through holes are not formed.
Forming a second through-hole conductor inside the plurality of second through holes, and
Forming a third plating film on the first copper foil exposed from the first plane and on the first through-hole conductor, and
Forming a fourth plating film on the second copper foil exposed from the second plane and on the first through-hole conductor, and
By removing a part of the third plating film and the second through-hole conductor, the first copper foil, the first through-hole conductor, and the second through-hole conductor are formed on the first surface side. Forming a third plane and
By removing a part of the fourth plating film and the second through-hole conductor, the second copper foil, the first through-hole conductor, and the second through-hole conductor are formed on the second surface side. Forming the fourth plane and
Forming a fifth plating film on the first copper foil exposed from the third plane, on the first through-hole conductor, and on the second through-hole conductor.
Forming a sixth plating film on the second copper foil exposed from the fourth plane, on the first through-hole conductor, and on the second through-hole conductor.
Forming the first conductor circuit from the fifth plating film and
Forming a second conductor circuit from the sixth plating film and
A method of manufacturing a printed wiring board including at least. In the method for manufacturing a printed wiring board according to claim 1, the formation of the first through-hole conductor, the formation of the first plating film, and the formation of the second plating film are performed at the same time. Forming the second through-hole conductor, forming the third plating film, and forming the fourth plating film are performed at the same time, and forming the fifth plating film and forming the sixth plating film. The formation is done at the same time. The method for manufacturing a printed wiring board according to claim 1 or 2, wherein a part of the first plating film and the first through-hole conductor is removed, and the second plating film and the first through-hole conductor are used. Removing a part, removing a part of the third plating film and the second through-hole conductor, and removing a part of the fourth plating film and the second through-hole conductor are possible. It is done by polishing or etching. The method for manufacturing a printed wiring board according to any one of claims 1 to 3, wherein the first conductor circuit is formed from the fifth plating film and the second conductor circuit is formed from the sixth plating film. This is done by the subtractive method or the semi-additive method. The method for manufacturing a printed wiring board according to any one of claims 1 to 4, wherein the first pitch of the first through hole is 600 μm or more, and the second through hole with respect to the adjacent first through hole. The second pitch is 300 μm or more. The method for manufacturing a printed wiring board according to any one of claims 1 to 4, wherein the plurality of first through holes have a hole diameter of 150 μm or more and 300 μm or less, and the plurality of second through holes have a hole diameter of 100 μm or more and 200 μm. It is as follows.

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